/Engine/Source/Runtime/Engine/Public/Net/NetPacketNotify.h
Gets the delta between the present sequence, and the sequence inside the specified header - if the delta is positive
[SequenceNumberT::DifferenceT](API\Runtime\Engine\Net\Util\TSequenceNumber\DifferenceT) GetSequenceDelta ( const [FNotificationHeader](API\Runtime\Engine\Net\FNetPacketNotify\FNotificationHeader) & NotificationData )